Method of producing reinforced, formed fabrics

ABSTRACT

The invention relates to a method of producing reinforced, formed fabrics, consisting in producing a continuous fabric alternated with a membrane ( 34 ) containing embedded reinforcing elements, which is prepared in overlapping portions on a conveyor belt ( 29 ) which passes over a preparation table ( 25 ). The membrane ( 34 ) and the reinforcing elements are then positioned under a press consisting of an upper air-filled chamber ( 1 ), the lower pait thereof comprising a flexible element ( 4 ), and a lower water-filled chamber ( 14 ), the upper part thereof comprising a flexible element ( 17 ). According to the invention, a forming bar ( 10 ) is adjustably mounted in the upper chamber ( 1 ). When the aforementioned forming bar ( 10 ) is adjusted to adopt a particular shape, the different flexible elements can deform at the forming bar and the membrane and the reinforcing elements are hot pressed with a portion corresponding to the forming bar having a threedimensional shape, thereby defining the form of the fabric produced.

The present invention relates to a method of manufacturing shaped andreinforced fabrics, and more particularly to a method of manufacturingshaped and reinforced fabrics continuously in alternation, the fabricbeing constituted by composite elements which are constituted by amembrane, impervious for example, which encases reinforcing elements,threads for example, the elements constituting the fabric being capableof being shaped in three dimensions so that the fabric has a desiredshape in three dimensions.

Reinforced and shaped fabrics are used in all cases where a fabric hasto be reinforced generally and in particular when a fabric has to bereinforced in particular directions which are determined by the forcesthat act on the fabric. By way of example, when a fabric acted ongreatly by forces comprises fixing eyelets at the location of itscorners or elsewhere, reinforcements may be necessary to distribute theforces, maintain the shape and avoid tears. Moreover, if large forcesact between one or other of the eyelets, reinforcements may be necessaryin the direction of the forces.

In many cases, it is necessary for the fabric to have particular shapesin three dimensions whether for reasons of performance or for aestheticreasons.

The manufacture of high-performance reinforced and shaped fabrics issubject to several parameters including of course commercial criteriawhich require that a fabric must be high-performance, as light aspossible and of course with a price as low as possible.

Many embodiments of reinforced and shaped fabrics and of reinforced andshaped fabric manufacture are known but they all have many drawbacks.

A basic drawback of all the known high-performance reinforced and shapedfabrics is that the structure of the fabric is constituted by anassembly of elements of the sandwich type, that is to say the fabricconsists of at least three components, these being the reinforcingelements which are assembled by bonding in a sandwich between twopolymerised plastic sheets, for example. This type of fabricconstruction is expensive and has a fairly heavy weight. The polymerisedplastic sheets are semi-rigid and may not allow local deformations. Theoverall shape of the fabric must allow a desired shape to be obtainedover the whole dimension of the fabric which consequently requiresmoulds with the total size of the bonded mat which are very expensive.These manufacturing methods with total-size moulds have severaldrawbacks, one of the greatest of which is the cost which is inevitablycarried over to the end product. Another drawback is the spacerequirement of these moulds which require very large productionpremises. Moreover, the large cost of the tools implies a lack offlexibility when changes in shape are necessary which slows down thedevelopment phases and makes them very expensive. As the reinforcingthreads are generally each placed in one piece with these embodiments,the positioning is very tricky.

Other known embodiments are implemented by assembling several fabricpanels from different cuts, the panels being assembled together bysewing or bonding. The location of the sewing is fragile and requiresreinforcing panels themselves added on by sewing. The forces to whichthe fabric is subjected are therefore dependent on the strength of thesewing at these locations which, as said, has the drawback of requiringreinforcing panels which contribute towards increasing the overallweight of the fabric. Moreover, at the locations of the sewing and thereinforcing panels, the fabric is less flexible than the other panels ofthe fabric, which causes many creases and fatigue of the materials whenthe fabric takes the desired shape, which is unsightly and can reducethe performance of the fabric for certain forms of use.

The aims of the present invention therefore consist of remedying theaforementioned drawbacks of the known embodiments.

The aims are achieved according to the principles of the invention asdescribed in claim 1.

The method of manufacturing shaped and reinforced fabrics according tothe principles of the invention consists of carrying out the manufactureof the fabric continuously. A press of small width compared with thelength of the fabric successively presses the constituent elements ofthe fabric. Reinforcing elements, threads for example, are prepared on abelt which is disposed able to move on a preparation table anddiscontinuous reinforcing elements are disposed overlapping the waitingpart of the fabric already pressed. The reinforcing elements can thus bedisposed in all directions according to the direction and magnitude ofthe forces to which the fabric is subjected. The upper and lowerchambers of the press comprise movable and adjustable devices which makeit possible to obtain, during pressing, a desired shape in threedimensions at desired locations. By successive forward movements of thefabric and depending on the adjustments, the fabric can have flatportions or have portions in three dimensions, and the shape of theportions in three dimensions can be varied quickly according to thefinal shape provided for the fabric. The elements that constitute thefabric consist of threads which are encased by a membrane which isconstituted by resin. Before pressing, these elements are in the form ofstrips which can be constituted by a prepreg of resin and threads, thepreimpregnation having the advantage of holding the threads. Oncepressed, the fabric is constituted by the membrane which is the resinwhich encases the threads or rather the filaments of the threads. Infact the threads are constituted by thousands of filaments which aredistributed over the width of each strip. During preparation, part ofeach strip is placed on the juxtaposed strips and during pressing thefilaments of the different strips intermix so as to constitute ahomogeneous and impervious fabric for example.

The principles of the invention have many advantages. One of the majoradvantages is that the fabric once completed is constituted, in section,by two elements, these being the membrane and the reinforcing filaments,and consequently the manufacturing method allows the elements to bereduced in comparison with the known three-layer embodiments. Thisreduction in the number of elements makes it possible to obtain areduction in the weight and cost.

The fact that the completed fabric is in the form of a membrane encasingthousands of intermixed filaments makes it possible to obtain a highlyhomogeneous fabric, with no creases and with reinforcements which makeit possible to withstand all the forces to which the fabric can besubjected. The membrane and the filaments also have the advantage ofbeing practically indeformable in the direction of the forces whilstbeing highly flexible during folding of the fabric for example.

The press has a very small space requirement compared with thedimensions of fabrics to be manufactured which makes it possible toinstall it in premises of small dimensions.

The shaping device integrated with the press which makes it possible toobtain portions of fabric in three dimensions, which makes it possibleto obtain a finished fabric in three dimensions, has many advantages.One of these advantages is that the shaping device makes it possible toeliminate the expensive tools such as the three-dimensional moulds ortools. This is because the shaping device can allow a multitude ofdifferent shapes to be obtained by simple and very quick adjustments.This advantage is very important during manufacture but is also veryimportant during the development of new fabrics having new shapes, theadjustment device making it possible to obtain a new shape very quicklyby simple and quick adjustments.

The principles of the invention make it possible to considerably reducethe manufacturing costs whilst making it possible to obtain higherperformance fabrics.

The accompanying figures illustrate schematically and by way of examplethe principles of the invention.

FIG. 1 is an overall side view of the press and the various elementsattached to the press.

FIG. 2 is a front view of the press with the shaping device.

FIG. 3 is an overall side view of the press with the shaping device inthe shaping position.

FIG. 4 is a front view of the press with the shaping device in theshaping position.

FIG. 5 is a view of the press with an infrared heating device.

FIG. 6 is a sectional view of a membrane encasing threads disposedunidirectionally.

FIG. 7 is a sectional view of a membrane encasing threads disposedmultidirectionally.

FIG. 8 is a plan view of strips before pressing.

FIG. 9 is a plan view of a fabric with strips disposed in differentdirections.

FIG. 10 is a sectional view of portions of fabric shaped in threedimensions.

FIG. 11 is a sectional side view of a spread-out fabric.

With reference first of all to FIG. 1, a press is constituted by anupper chamber 1 and a lower chamber 14. The lower chamber 14 comprisesL-shaped angle irons 15 and 16. The upper part of the lower chamber 14comprises a flexible element 17 (a silicone membrane for example) whichis mounted hermetically on the lower chamber 14. The lower chamber 14 isfilled with water 18 which is brought via a water inlet 24. The waterinlet is controlled by a valve 35. The lower chamber comprises a wateroutlet 19 which is a balancing outlet. The water outlet 19 is connectedby a duct to a tank 20 which contains water 21. The tank comprises awater overflow 23 which determines the height of the water level 22. Theheight of the water level 22 is provided to be at the level of the lowerface of the flexible element 17. The water level in the lower chamber isthus controlled by the communicating vessels principle. A valve 58 ismounted between the water outlet 19 and the tank 20. Closing of thevalve 58 makes it possible to block off the water circulation and annulthe communicating vessels principle. A balancing tank 59 is placed underthe overflow 23. When water overflows via the overflow 23 into thebalancing tank 59, the surplus water in the balancing tank is constantlytaken back into the tank 20 via a duct 61 which is connected to a pump60. The upper chamber 1 is closed off in its lower part by a flexibleelement 4 which is mounted hermetically with the upper chamber. Theupper chamber contains air 5 which is brought via an air inlet 6. Thepressure of the air is controlled by a manometer 11. The upper chamber 1comprises reinforcing elements 2. A metal girder 3 is mounted on thereinforcing elements, the whole being assembled by welding for example.The metal girder 3 is connected to an actuator or to any mechanicaldevice whatsoever making it possible on the one hand to lift up thechamber during the preparation operations or to apply a pressuredownwards during the pressing operation. A threaded rod 7 whichcomprises an activation nut 8 cooperates with a tapped element 9 whichis mounted on the upper chamber. The lower end of the rod is connectedwith play to a shaping bar 10. A preparation table 25 is mounted on feet26 and a receiving table 27 is mounted on feet 28. A conveyor belt 29 ismounted able to move on the tables and on the flexible element 17 of thelower chamber 14. The conveyor belt is supported by two fixed rollers 30and 31 and by a movable roller 32 which is subject to the action of adraw spring 33 which adjusts the tension of the conveyor belt 29according to the deformations thereof. The reinforced strips 34 whichconstitute the fabric once the pressings have been performed areprepared on the conveyor belt, and then pass under the press and comeout in the form of a fabric constituted by a membrane which encasesfilaments.

FIG. 2 shows in a front view the threaded rods 36, 37, 7, 38, 39, whichare connected in their lower part to the shaping bar 10. The shaping baris not fixed to the rods in its longitudinal direction, but is mountedable to move so that when the shaping bar is deformed the tensions on itcan be absorbed. FIG. 2 shows the metal girder 3, the upper chamber 1 inwhich the shaping bar is installed and the reinforcing elements 2 of theupper chamber, the flexible elements 4 and 17, the water inlet 24, thebalancing water outlet 19, the air inlet 6, the lower chamber 14, theconveyor belt 29 and the roller 30 and the reinforced strips 34.

The position shown in FIGS. 1 and 2 is the flat pressing position inwhich the shaping bar is in the inactive position. In this position, thewater in the lower chamber is kept at its level by the communicatingvessels principle and then the valve 58 is closed, and the air containedin the upper chamber is put under pressure, at a pressure value which isdetermined by the kind of resin of the reinforced strips.

During the pressing, the resin must be heated to or activated at atemperature determined by the kind of resin. Several heatingpossibilities can be provided according to FIG. 1. One possibility isheating of the air contained in the upper chamber. One possibility isheating of the water contained in the lower chamber. One possibility isheating of the preparation table just before the reinforced strips aremoved under the press.

For the case where the heating is not obtained by the preparation table,this table is in any case heated to a certain temperature necessary fora slight adhesion of the reinforced strips in order to facilitate theputting down of these strips.

FIG. 1 shows an immobilising element 12 which is activated by animmobilising actuator 13. In the position of movement of the conveyorbelt, the immobilising element is inactive.

In practice, the first reinforced strips are disposed on the preparationtable. Once the reinforced strips have been put down, the conveyor beltplaces these first reinforced strips under the press, the upper chamberis moved towards the base until contact with pressure is made on thelower chamber, by heating and the air pressure in the upper chamber thereinforced strips are converted into a membrane encasing filaments, thewhole constituting an impervious or pervious fabric. One or bothchambers are cooled, thus cooling the membrane. Movement of thereinforced strips by the conveyor belt leaves a portion of the strips onthe preparation table for connection with the second series ofreinforced strips. During the time of pressing the first reinforcedstrips, the second strips are disposed on the preparation table and whenthe operation of pressing the first reinforced strips is accomplished,the air pressure is reset to ambient pressure, the upper chamber islifted up and the second reinforced strips are placed under the press.The manufacturing time for a fabric is determined by the time necessaryfor heating of the reinforced strips and cooling. By way of example,according to the resins used, the pressing time can be limited to a fewminutes which are necessary in any case for disposition of the nextreinforcing strips.

FIGS. 3 and 4 show the pressing of a portion of reinforced strips withshaping in three dimensions. In this case, when the reinforced strips 34are installed under the press, the rods 36, 37, 7, 38, 39, areactivated, for example by means of nuts such as the nut 8 so as to givean arc shape to the bar 10. The immobilising element 12 is activated bythe immobilising actuator 13 and immobilises the portion of fabricalready completed. In this way, the threads of the reinforced strips cantake the shape provided for, and therefore the resulting difference inlength of the third dimension. During the pressing with shaping, theflexible elements 4 and 17 and the conveyor belt 29 also take the chosenshape. The movable roller 32 moves upwards while maintaining the tensionin the conveyor belt by the spring 33. The shaping position, andtherefore the movement of the shaping bar 10 downwards, reduces thevolume of the lower chamber 14 and the excess water 18 can leave via thewater outlet which goes into the tank 20 and overflows via the overflow23. The valve 58 is closed immobilising the quantity of water in thechamber 14, and the air 5 is put under pressure.

When the pressing is complete, the shaping bar is replaced into theinactive position, the valve 58 is opened, the water is put back to itslevel by the pump 60 which takes the excess water contained in thebalancing tank 59 back into the tank 20 via the duct 61. The otherpressing operations are identical to the flat pressing operations.

In practice and with the aim of obtaining the desired finished fabricshape in three dimensions, some portions of the fabric are pressed flat,and others with various shapes of the shaping bar.

FIG. 5 shows another heating possibility with infrared heating elements40 and 41 which are disposed in the upper chamber.

FIG. 6 shows a portion of fabric with the membrane 42 which encases thethreads 43 disposed unidirectionally. In practice and after pressing,the threads are in fact constituted by thousands of filaments.

FIG. 7 shows a portion of fabric with the membrane 46 encasing warpthreads 44 and weft threads 45 multidirectionally.

FIG. 8 shows in plan view the reinforced strips 34 which are disposed onthe conveyor belt 29 which is placed on the preparation table withpassage under the press depicted in this figure by the upper chamber 1.FIG. 8 shows different sorts of unidirectional 47 or bidirectional 48reinforced strips which can be used by way of example.

FIG. 9 is a plan view of a fabric which shows a few examplepossibilities of disposition of reinforced strips, that is thereinforced strips 49, 50, 51, 52, which make it possible to obtainstrength in an arc, the strip 53 which has a reinforcement at 90°, orstrips 55 and 54 which can be disposed at the location of an eyelet 56for example.

FIG. 10 shows a sectional view of a fabric with portions deformed inthree dimensions according to FIG. 4 in the non-taut position.

FIG. 11 shows the three-dimensional shape taken by the fabric when it istaut.

The various activation elements, the threaded rods, the movements of theupper chamber, the forward movement of the conveyor belt, theimmobilising element, opening and closing of the water supplies andoutlets, switching on and off of the heating, and the air pressure, canbe obtained by electric motors, step-by-step motors for example,actuators, valves or electrical controls. Each of these elements can beconnected to a computer whose program manages the activation. It is alsopossible to dispose the reinforced strips by a transport and placingdevice which can also be managed by the computer program.

In this way, the manufacture of the fabric can be fully automatic.

There are numerous uses for fabrics in three dimensions, and thesefabrics can be used in all cases requiring light, very strong andthree-dimensional fabrics.

1. A method of manufacturing shaped and reinforced fabrics,characterised by the fact that it consists of manufacturing a fabricconsisting of a membrane (34) which encases reinforcing elementscontinuously in alternation in a press which comprises an upper chamber(1) whose lower part is constituted by a flexible element (4) and alower chamber (14) whose upper part is constituted by a flexible element(17), the upper chamber (1) comprising a shaping bar (10) whose shapecan be adjusted by adjustment rods (7) and whose adjustment shape causesthe elastic deformation in three dimensions of the flexible elements (4and 17) and consequently of the membrane and the reinforcing elementswhich are in the press, into an active position in which the bar has ashape and into an inactive position in which the shaping bar is inactiveand causes no deformation of the membrane and the reinforcing elementswhich are pressed flat, by the fact that the portions of membrane andreinforcing elements are prepared before pressing on a conveyor beltwhich is put on a preparation table (25) which then places theseportions under the press with pressure and heating, and by the fact thatthe portions of membrane and reinforcing elements are overlapped duringthe preparation so as to constitute at the output of the press ahomogeneous fabric which comprises flat portions and portions shaped inthree dimensions according to multiple shapes determined by theadjustment of the shaping bar during the pressing of each portion ofmembrane and reinforcing elements whose length is determined by thewidth of the press and of the preparation table.
 2. A manufacturingmethod according to claim 1, characterised by the fact that the upperchamber of the press is filled with air whose pressure is adjustable andcontrolled by a manometer, the pressing pressure being provided by thecompressed air contained in the upper chamber.
 3. A manufacturing methodaccording to claim 1, characterised by the fact that the lower chamberis filled with water whose level is maintained by the communicatingvessels principle by linking of the water supply and outlet (19) whichis connected to a tank (20), and whose pressure is maintained duringpressing by closure of the valve (58).
 4. A manufacturing methodaccording to claim 1, characterised by the fact that polymerisation oractivation of the resin constituting the membrane is obtained by heatingthe preparation table.
 5. A manufacturing method according to claim 1,characterised by the fact that activation of the resin is obtained byheating the preparation table and that polymerisation is obtained byheating one or other of the chambers.
 6. A manufacturing methodaccording to claim 1, characterised by the fact that activation orpolymerisation of the resin is obtained by heating the press.
 7. Amanufacturing method according to claim 1, characterised by the factthat the portions of membrane and reinforcing elements are placedpartially overlapping one another so as to guarantee the homogeneity ofthe fabric.
 8. A manufacturing method according to claim 1,characterised by the fact that the portions of membrane and reinforcingelements can be disposed in all directions and also one upon another bycrossing according to the direction of the forces to which the fabric issubjected and according to the locations where the fabric has tocomprise particular reinforcements.
 9. A manufacturing method accordingto claim 1, characterised by the fact that an element (12) forimmobilising the fabric is activated during the pressing.